Previous value: -"Change indicator: FM (from), TEMPO (temporary), BECMG (becoming), or null for the base period."New value: +"Change indicator: FM (from), TEMPO (temporary), BECMG (becoming), PROB (a standalone probability group), or null for the base period. A PROB30 or PROB40 qualifying a temporary group arrives as TEMPO; standing alone, with no temporary group after it, it arrives as PROB. Either way the percentage is in probability."

Previous value: -"Forecast cloud layers for this period."New value: +"Forecast cloud layers for this period. Empty whenever the period published no layer heights, which covers a forecast clear sky and a period carrying no cloud element at all; sky_condition distinguishes them. An empty array is not a forecast of a clear sky on its own."

Added value: +{
+  "description": "The sky condition this period forecast when it published no layer heights: SKC or NSC for a clear or insignificant-cloud forecast (a CAVOK group arrives as NSC), OVX for a forecast obscuration carrying no vertical visibility. Null when clouds carries layers — those are the statement — and also when the period carried no cloud element at all. An empty clouds array beside a null here forecasts nothing about cloud; on a TEMPO, PROB, or BECMG group that means the prevailing forecast stands unchanged, never that the sky will be clear.",
+  "type": [
+    "string",
+    "null"
+  ]
+}

Previous value: -[
-  "from",
-  "to",
-  "change_type",
-  "probability",
-  "wind",
-  "wind_shear",
-  "visibility_sm",
-  "vertical_visibility_ft",
-  "weather",
-  "clouds"
-]New value: +[
+  "from",
+  "to",
+  "change_type",
+  "probability",
+  "wind",
+  "wind_shear",
+  "visibility_sm",
+  "vertical_visibility_ft",
+  "weather",
+  "clouds",
+  "sky_condition"
+]

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

Added value: +[
+  "string",
+  "null"
+]

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

Added value: +[
+  "string",
+  "null"
+]

Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]

Added value: +[
+  "number",
+  "null"
+]

Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]

Added value: +[
+  "number",
+  "null"
+]

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

Added value: +[
+  "string",
+  "null"
+]

Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]

Added value: +[
+  "number",
+  "null"
+]

Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]

Added value: +[
+  "number",
+  "null"
+]

Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]

Added value: +[
+  "number",
+  "null"
+]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "forecasts",
+      "requested",
+      "returned",
+      "partial"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `no_taf_available`: Station does not issue TAFs or no TAF is currently available. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "no_taf_available"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "forecasts",
-  "requested",
-  "returned",
-  "partial"
-]

Previous value: -"Cloud base altitude in feet AGL."New value: +"Cloud base altitude in feet AGL. On an OVX layer this is the vertical visibility into the obscuration rather than a layer bottom, and 0 is a surface-level indefinite ceiling."

Previous value: -"Sky cover code: FEW, SCT, BKN, OVC, SKC, CLR."New value: +"Sky cover code: FEW, SCT, BKN, OVC, SKC, or OVX. OVX is the decoded form of a VVhhh group — the sky is obscured and the base is the vertical visibility into it, not a cloud bottom."

Previous value: -"Cloud type qualifier: CB (cumulonimbus), TCU (towering cumulus), or null."New value: +"Cloud type qualifier: CB (cumulonimbus), TCU (towering cumulus), or null. An obscuration can carry one — a VV008CB group is an OVX layer with type CB."

Added value: +{
+  "anyOf": [
+    {
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Vertical visibility into a forecast obscuration, in feet AGL — an indefinite ceiling, and the same height as this period OVX cloud layer. 0 is a surface-level indefinite ceiling; null means the period forecasts no obscuration."
+}

Previous value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "properties": {
+      "decoded": {
+        "description": "Plain-English reading of each group, joined with \"; \" (e.g., \"light rain showers; mist\"). A group the decoder does not recognize is carried through as its own raw token rather than half-translated, so compare against raw when a reading still looks coded.",
+        "type": "string"
+      },
+      "raw": {
+        "description": "Weather groups exactly as forecast, space-delimited (e.g., \"-SHRA\", \"-SHRA BR\", \"VCTS -RA\").",
+        "type": "string"
+      }
+    },
+    "required": [
+      "raw",
+      "decoded"
+    ],
+    "type": "object"
+  },
+  {
+    "type": "null"
+  }
+]

Previous value: -"Decoded weather condition (e.g., \"light rain showers\", \"thunderstorm with rain\"). Null if none."New value: +"Forecast weather for this period, or null when the period carried no weather group."

Previous value: -"Forecast wind conditions for this period."New value: +"Forecast wind conditions at the surface for this period."

Added value: +{
+  "anyOf": [
+    {
+      "additionalProperties": false,
+      "properties": {
+        "direction_deg": {
+          "description": "Forecast wind direction at the top of the shear layer, in degrees true — not a direction of shear.",
+          "type": "number"
+        },
+        "height_ft": {
+          "description": "Top of the shear layer in feet AGL — not the layer base and not its thickness. A WS020 group is 2000 ft.",
+          "type": "number"
+        },
+        "speed_kt": {
+          "description": "Forecast wind speed at the top of the shear layer, in knots — the wind at that height, not the magnitude of the shear.",
+          "type": "number"
+        }
+      },
+      "required": [
+        "height_ft",
+        "direction_deg",
+        "speed_kt"
+      ],
+      "type": "object"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Forecast non-convective low-level wind shear (a WS group), confined to the surface–2,000 ft AGL band. A null means no non-convective LLWS group was issued for this period, rather than no shear expected: the group is excluded from TEMPO and PROB groups, and shear is always assumed present in convective activity."
+}

Previous value: -[
-  "from",
-  "to",
-  "change_type",
-  "probability",
-  "wind",
-  "visibility_sm",
-  "weather",
-  "clouds"
-]New value: +[
+  "from",
+  "to",
+  "change_type",
+  "probability",
+  "wind",
+  "wind_shear",
+  "visibility_sm",
+  "vertical_visibility_ft",
+  "weather",
+  "clouds"
+]

Added value: +{
+  "description": "Requested station IDs absent from the result. Absent when none are missing.",
+  "items": {
+    "description": "A requested ICAO station ID that produced no forecast.",
+    "type": "string"
+  },
+  "type": "array"
+}

Added value: +{
+  "description": "Recovery guidance naming the missing station IDs. Present only on a partial result. It lists the candidate causes without asserting one — upstream omits the row either way.",
+  "type": "string"
+}

Added value: +{
+  "description": "True when a requested station produced no forecast. False affirms the result covers every requested station, so full coverage is distinguishable from a short batch rather than being inferred from the count.",
+  "type": "boolean"
+}

Added value: +{
+  "description": "Station IDs this call asked for, in the order given.",
+  "items": {
+    "description": "An ICAO station ID as requested.",
+    "type": "string"
+  },
+  "type": "array"
+}

Added value: +{
+  "description": "Distinct station IDs that produced a forecast.",
+  "items": {
+    "description": "An ICAO station ID present in the result.",
+    "type": "string"
+  },
+  "type": "array"
+}

Previous value: -[
-  "forecasts"
-]New value: +[
+  "forecasts",
+  "requested",
+  "returned",
+  "partial"
+]

Previous value: -"Cloud base altitude in feet MSL."New value: +"Cloud base altitude in feet AGL."

Previous value: -"Forecast wind direction in degrees true. Null when variable."New value: +"Forecast wind direction in degrees true. Null when the forecast said VRB (variable), and also when the period carries no wind element at all — speed_kt is null in that second case and a number in the first."

Added value: +[
+  {
+    "type": "number"
+  },
+  {
+    "type": "null"
+  }
+]

Previous value: -"Forecast wind speed in knots."New value: +"Forecast wind speed in knots. 0 is a forecast calm (a 00000KT group); null means the period amends only visibility, weather, or cloud and carries no wind element, so the wind is unknown rather than calm."

Removed value: -"number"